G51.9: Disorder of facial nerve, unspecified
G51.9, disorder of facial nerve, unspecified, is listed as a covered diagnosis in 4 Medicare billing and coding articles that apply to 13 HCPCS Level II codes, including G0340 (Image-guided robotic linear accelerator-based stereotactic…), G0339 (Image-guided robotic linear accelerator-based stereotactic…), G0563 (Stereotactic body radiation therapy, treatment delivery…). The articles come from 2 Medicare contractors. A listed diagnosis supports medical necessity only; coverage still depends on the LCD's criteria and on documentation in the medical record.
HCPCS Level II codes with G51.9 as a covered diagnosis
| Code | Description | Medicare coverage | DMEPOS fee 2026 (state range) | Articles listing it |
|---|---|---|---|---|
| G0340 | Image-guided robotic linear accelerator-based stereotactic radiosurgery, delivery including collimator changes and custom plugging, fractionated treatment, all lesions, per session, second through fifth sessions, maximum five sessions per course of treatment | Carrier judgment | — | 1 |
| G0339 | Image-guided robotic linear accelerator-based stereotactic radiosurgery, complete course of therapy in one session or first session of fractionated treatment | Carrier judgment | — | 1 |
| G0563 | Stereotactic body radiation therapy, treatment delivery, per fraction to 1 or more lesions, including image guidance and real-time positron emissions-based delivery adjustments to 1 or more lesions, entire course not to exceed 5 fractions | Carrier judgment | — | 1 |
| G2187 | Patients with clinical indications for imaging of the head: head trauma | Carrier judgment | — | 1 |
| G2188 | Patients with clinical indications for imaging of the head: new or change in headache above 50 years of age | Carrier judgment | — | 1 |
| G2189 | Patients with clinical indications for imaging of the head: abnormal neurologic exam | Carrier judgment | — | 1 |
| G2190 | Patients with clinical indications for imaging of the head: headache radiating to the neck | Carrier judgment | — | 1 |
| G2191 | Patients with clinical indications for imaging of the head: positional headaches | Carrier judgment | — | 1 |
| G2192 | Patients with clinical indications for imaging of the head: temporal headaches in patients over 55 years of age | Carrier judgment | — | 1 |
| G2193 | Patients with clinical indications for imaging of the head: new onset headache in pre-school children or younger (<6 years of age) | Carrier judgment | — | 1 |
| G2194 | Patients with clinical indications for imaging of the head: new onset headache in pediatric patients with disabilities for which headache is a concern as inferred from behavior | Carrier judgment | — | 1 |
| G2195 | Patients with clinical indications for imaging of the head: occipital headache in children | Carrier judgment | — | 1 |
| G0255 | Current perception threshold/sensory nerve conduction test, (snct) per limb, any nerve | Non-covered by Medicare | Not covered | 2 |
Medicare policy articles listing G51.9
- A56874: Billing and Coding: Stereotactic Radiation Therapy: Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT) (Wellpoint Federal (MAC - Part A, MAC - Part B); 3 Level II codes). LCD with the same title: L35076
- A57668: Billing and Coding: Nerve Conduction Studies and Electromyography (Wellpoint Federal (MAC - Part A, MAC - Part B); 1 Level II codes). LCD with the same title: L34594, L34859, L35048, L35081
- A56619: Billing and Coding: Nerve Conduction Studies and Electromyography (Palmetto GBA (MAC - Part A, MAC - Part B); 1 Level II codes). LCD with the same title: L34594, L34859, L35048, L35081
- A56612: Billing and Coding: CT of the Head (Palmetto GBA (MAC - Part A, MAC - Part B); 9 Level II codes). LCD with the same title: L34417
A diagnosis listed as covered in a billing and coding article supports medical necessity for the article's codes; it does not guarantee payment. Coverage depends on the LCD's criteria, the contractor's jurisdiction and documentation in the medical record.
Other G51 diagnoses (Facial nerve disorders)
- G51.0 — Bell's palsy
- G51.1 — Geniculate ganglionitis
- G51.2 — Melkersson's syndrome
- G51.31 — Clonic hemifacial spasm, right
- G51.32 — Clonic hemifacial spasm, left
- G51.33 — Clonic hemifacial spasm, bilateral
- G51.4 — Facial myokymia
- G51.8 — Other disorders of facial nerve
Frequently asked questions
Does Medicare cover G51.9 (Disorder of facial nerve, unspecified)?
Medicare covers items and services, not diagnoses. 4 Medicare billing and coding articles list G51.9 as a covered diagnosis for 13 HCPCS Level II codes: the diagnosis can support medical necessity for those codes, but payment still depends on the LCD's coverage criteria and the medical record.
Which HCPCS codes can be billed with ICD-10 G51.9?
The Level II codes from the policies most specific to this diagnosis are G0340 (Image-guided robotic linear accelerator-based stereotactic…, 1 article); G0339 (Image-guided robotic linear accelerator-based stereotactic…, 1 article); G0563 (Stereotactic body radiation therapy, treatment delivery…, 1 article); G2187 (Patients with clinical indications for imaging of the…, 1 article); G2188 (Patients with clinical indications for imaging of the…, 1 article). Code choice depends on the item supplied; check each code's descriptor.
Which Medicare policy articles list G51.9?
A56874 (Billing and Coding: Stereotactic Radiation Therapy: Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT)); A57668 (Billing and Coding: Nerve Conduction Studies and Electromyography); A56619 (Billing and Coding: Nerve Conduction Studies and Electromyography), and 1 more article.
What is ICD-10-CM code G51.9?
G51.9 is the ICD-10-CM code for disorder of facial nerve, unspecified, in category G51 (Facial nerve disorders), chapter 6: Diseases of the nervous system.
Next steps
- Run a reimbursement report for a device billed under G0340
- Watch G0340 for fee, coverage and descriptor changes
- Build a full Medicare revenue model for G0340
Sources: CMS Medicare Coverage Database billing and coding articles (covered ICD-10 code lists and HCPCS links); ICD-10-CM FY2026; CMS HCPCS Level II release October 2026; CMS DMEPOS fee schedule 2026 (non-rural state fees). Not billing or legal advice.
Chapter 6: Diseases of the nervous system · All diagnoses · HCPCS lookup